Explosive initiators



1962 s. v. PEYTON ETAL 3,015,275

EXPLOSIVE INITIATORS Filed Sept. 3. 1958 Invergor; 5 p a if/14 19 3,015,275 EXPLOSIVE INITIATORS Stanley Victor Peyton, 18 Croft Way, Sevenoaks, England, and Edward Williams, Muriau Gwyn, Abbey Drive, Gronant, Prestatyn, Wales Filed Sept. 3, 1958, Ser. No. 758,863 Claims priority, application Great Britain Sept. 3,

1 Claim. (Cl. 102-70) This invention relates to initiators for high explosive systems.

initiators at present in use commonly contain a small quantity of a primary detonant, such as lead azide and a pellet of a secondary explosive such as tetryl the two being connected by a stem of the secondary explosive packed into a narrow channel in a suitable casing. The use of lead azide has certain disadvantages including instability during long storage and a tendency, when stored in contact with copper or brass components, to form the dangerously sensitive copper azide.

In order to overcome these disadvantages in an initiator in accordance with the invention the primary detonant is replaced by a violent igniferous composition such as lead styphnate which is considerably more stable in storage and does not react with the adjacent metal parts of the initiator.

The invention therefore comprises an initiator for high explosive systems, wherein a violent igniferous composition is used in conjunction with'a channel filled with a secondary explosive and with a pellet of a secondary explosive and which contains an air gap allowing free communication between the violent igniferous composition and the secondary explosive at the instant of firing.

The violent ignifero-us composition may be lead styphnate or a mixture containing mercury fulrninate or lead dinitro-resorcinate. The filling for the channel may be pentaerythritol tetranitrate (hereinafter referred to as P.E.T.N.), cyclonite or tetryl while the pellet is preferably either cyclonite or tetryl" Mercury fulminate mixtures, have, however, certain disadvantages, such as incompatibility with aluminium and its alloys and a short storage life.

In a preferred form therefore the invention comprises an initiator for a high explosive system containing an explosive train consisting of a capsule of lead styphnate or a mixture containing lead dinitroresorcinate; a channel filled with P.E.T.N., cyclonite or tetryl and a pellet of cyclonite or tetryl; there being an air gap between the capsule and the explosive filling of the channel.

This form of initiator in which a violent igni-ferous composition replaces lead azide is considerably safer than the older type. Lead styphnate will not produce the desired ignition if placed in close contact with the secondary explosive and it is therefore necessary to have an air gap between them in order to ensure detonation.

If desired a safety shutter may be incorporated which when closed may conveniently lie across the air gap and be withdrawn when the initiator is required for use.

One form of initiator in accordance with the invention will now be particularly described, by way of example only, with reference to the accompanying drawing which is a longitudinal section of'an initiator having a shutter across the air gap.

The initiator has a casing 1, hereinafter referred to as the forward casing, and a casing 2 hereinafter referred A 3,015,275 Patented Jane 2, 1962 to as the rearward casing. The forward casing 1 has an axial cylindrical recess in its forward end into which is inserted a shell or capsule 3 containing a highly igniferous composition 4 which is preferably either lead styphnate or a mixture containing lead dinitroresorcinate. The capsule is closed by a disc 5 which may be of brass, aluminium, silk gauze or any of the commonly used materials; the disc 5 being held in place by a washer 6 which is retained by turning inwardly the forward end of the capsule 3. Rearward of the capsule, a bore 7 of smaller diameter than the capsule extends through the forward casing 1.

The rearward casing 2 has a longitudinal channel filled with a pressed explosive 8 which may be P.E.T.N., cyclonite or tetryl. The rearward end of the rearward casing 2 has a tubular extension 9 whose internal diameter is greater than that of the central channel and which has inserted therein a pellet 1% of explosive which is preferably either cyclonite or tetryl. Rearward of the pellet 10 is a closure disc 11 of any suitable material held in position by turning inwardly the rearmost end of the tubular extension 9. The forward end of the rearward casing is closed by a thin disc 12 of brass or aluminium.

Between the forward and rearward casings 1 and 2 is a gap across which is a shutter 13 having therein a hole indicated by the broken lines 14 which hole may be brought into axial alignment with the bore 7 of the forward casing 1 by any suitable action such as is commonly used in the operation of fuze shutters. When the hole in the shutter is so aligned it constitutes, with the bore 7 an air gap between the capsule 3 and the explosive 8 in the central channel of the rearward casing 2.

The casings 1 and 2 may have any suitable external contour for insertion into correspondingly shaped recesses in an explosive store such as a fuze for a bomb or shell, or they may be formed integrally with the body of a fuze. For some applications the casings 1 and 2 may be combined to form a single unit. The shutter may be omitted if desired in which case the air gap would be enclosed by an extension of either the forward or rearward casing.

We claim:

An initiator for high explosive systems comprising a forward casing, a capsule within a recess in the forward end of said casing, said capsule filled with lead styphnate, a rearward casing centrally spaced from the forward casing and attached thereto to provide an air gap therebetween, a central longitudinal channel in said rearward casing of less diameter than that of the recess in the forward casing, a column of P.E.T.N. within said longitudinal channel, an integral tubular rearward extension of the rearward casingpa recess in the tubular extension Whose internal diameter is greater than that of the channel, a pellet of cyclonite within said recess and located immediately rearward of the column of P,E.T.N. in said channel, a .sli-dable safety shutter having a port therethrough and occupying said air gap between said forward (References on following page) References Cited in the file of this patent UNITED STATES PATENTS Doran Aug. 19, 1919 Cartwright Feb. 24, 1920 5 Brayto n Dec. 9, 1924 Eschbach Jan. 5, 1932 Eschbach July 31, 1934 

